In the prior art, silicone putty compositions are generally prepared by mixing dimethylsilicone with boron oxide and heat treating the mixture at a temperature of 100 to 2500.degree. C. for forming a polymeric material having an increased viscosity as disclosed in Japanese patent publication No. 6944/1951. For use as putty, the polymer is blended with an appropriate amount of dimethylpolysiloxane, silica and the like to form a composition having an optimum plasticity. The silicone putty compositions thus prepared, however, must pass a structure forming time of several days to about one month from the mixing of the respective components before the silicone putty can provide certain impact resilience. That is, the conventional silicone putty compositions suffer from a wasteful storage period before use.
By blending such a silicone putty composition with silica such as fumed silica, precipitated silica or diatomaceous earth, there can be obtained silicone putty which exhibits high impact resilience from a relatively early stage. A relatively large amount of silica should be blended to this end. The resulting silicone putty composition is extremely highly plastic and hard. Because of unduly high hardness,, the composition is difficult to apply to toys and dampers.
There is a need for a silicone putty composition which exhibits high impact resilience from an early stage and provides a soft silicone putty having low plasticity.